This invention relates generally to a heat exchanger or more explicitly to a recuperator and more particularly to a method and an apparatus for testing the leakage within a core of the recuperator.
Many gas turbine engines use a heat exchanger or recuperator to increase the operation efficiency of the engine by retracting heat from the exhaust gas and preheating the intake air. Typically, a recuperator for a gas turbine engine must be capable of operating at temperatures of between about 500 degrees C. and 700 degrees C. and internal pressures of between approximately 450 kPa and 1400 kPa under operating conditions involving repeated starting and stopping cycles.
A recuperator is made from a plurality of cells. The cell is made from a plurality of components parts. The assembly of the plurality of cells form a core having a donor passage and a recipient passage. The components of the cell are welded together and tested for leakage and the plurality of cells are welded together forming the core. An example of such a plurality of welded cells resulting in the core is shown in U.S. Pat. No. 5,060,721 issued on Oct. 29, 1991 to Charles T. Darragh.
As stated above, during the assembly of the cells and the recuperator core, the interface of the components are welded. The effectiveness of the welding process used to form the core is in many instances depended on the fitting relationship of the plurality of cells, the resulting configuration of the interface of the individual ones of the plurality of cells and the welding process itself The results of these variables in some instances results in a leaking core, leakage between the donor passage and the recipient passage. Thus, it is necessary to inspect or check the reliability of the welded core against leaks prior to installing into the recuperator application. The inspection process adds cost to the finished core, which to insure reliability may be necessary, but the cost effectiveness of such an inspection process can reduce profitability. Inspection or checking must be done in a reliable and cost effective manner.
The present invention is directed to overcome one or more of the problems as set forth above.
In one aspect of the invention, an apparatus for testing a leakage rate within a recuperator core is disclosed. The recuperator core has a plurality of components, such components being a plurality of cells being welded one to another. The apparatus has a platform defining a first end and a second end. A first surface of the platform extends between the first end and the second end. A first support portion is attached to the first surface and a second support portion is spaced from the first support portion and each being attached to the first surface. A pair of sealing mechanisms, at least one of the pair of sealing mechanisms being movable between an open or non testing position and a closed or testing position. In the closed or testing position a reservoir is formed. A pump being operatively connected to at least one of the pair of sealing mechanisms. A monitoring system being operatively connected to the platform, the pair of sealing mechanisms, the reservoir and the pump. And, a readout station being operatively connected to the monitoring system, the reservoir and the pump.
In another aspect of the invention, a method of testing a recuperator core is disclosed. The recuperator core has a plurality of donor passages defining a donor inlet end and a donor outlet end and a plurality of recipient passages defining a recipient inlet end and a recipient outlet end. The plurality of donor passages are sealed from the plurality of recipient passages. The method of testing the recuperator core has the steps of positioning the recuperator core in a test stand; positioning a sealing member in sealing relationship with one of the donor inlet end and the recipient inlet end and positioning an other of the sealing member in sealing relationship with one of the donor outlet end and the recipient outlet end forming a reservoir and defining a closed or testing position; actuating a controller applying one of a pressure and a vacuum to the reservoir; monitoring a rate of decay of the pressure and the vacuum; and displaying the rate of decay.